WO2014103397A1 - Method for producing aqueous solution of perrhenic acid from rhenium sulfide - Google Patents

Abstract

Provided is a method that enables high-purity perrhenic acid to be produced from crude rhenium sulfide using a dry process. This method for producing an aqueous solution of perrhenic acid includes: 1) a step in which roasting is performed on rhenium sulfide in the presence of an oxygen-containing gas, and gasified rhenium oxide is collected; 2) a step in which the rhenium oxide is cooled and solidified, while keeping sulfur oxides associated with the gasified rhenium oxide in a gaseous state, and then the purity of the rhenium oxide is increased by performing solid-gas separation; and 3) a step in which an aqueous solution of perrhenic acid is obtained by dissolving the solidified rhenium oxide in water, or by dissolving the solidified rhenium oxide in water after heating and gasifying the solidified rhenium oxide.

Description

Method for producing perrhenic acid aqueous solution from rhenium sulfide

The present invention relates to a method for producing a perrhenic acid aqueous solution from rhenium sulfide. In particular, the present invention relates to a method for producing ammonium perrhenate from rhenium sulfide via perrhenic acid.

Rhenium is a rare metal slightly associated with molybdenite or copper ore, but it is an important metal used as an additive element for catalysts, additive elements for thermocouples and superalloys, high vacuum electron tube materials, etc. It is.

Crude rhenium sulfide is one of the promising raw materials for industrially recovering rhenium. Typical impurities in the crude rhenium sulfide include zinc and bismuth.

Conventionally, as described in JP-A-62-148327 (Patent Document 1), a method for producing potassium perrhenate from crude rhenium sulfide is known. In this document, crude rhenium sulfide is oxidized and leached using an oxidant such as hydrogen peroxide, and hydrogen sulfide is added to the liquid after leaching, thereby obtaining a high purity perrhenic acid in the rear liquid. Potassium perrhenate is produced by adding potassium hydroxide. From potassium perrhenate, as described in JP-A-2-20575 (Patent Document 2), ammonium perrhenate is obtained by a method of neutralizing with ammonia water after contact with a cation exchange resin and filtering. Can be manufactured. Ammonium perrhenate can be traded as a valuable material and is a form with high added value.

Japanese Patent Application Laid-Open No. 47-21323 (Patent Document 3) discloses a molybdenum ore containing rhenium that is roasted and extracted with water, and potassium chloride is added to the extract. After dissolving in concentrated sulfuric acid and adjusting the sulfuric acid concentration to 1 to 3 mol, extract with an organic solvent containing a high molecular weight organic tertiary amine concentration of 0.02 mol or more, and then back extract this extract with caustic potash aqueous solution In addition, a method for producing rhenium is described in which the extract is concentrated and reduced.

In Patent Document 3, rhenium is contained in the form of rhenium sulfide. By roasting, rhenium sulfide is oxidized into rhenium oxide (Re ₂ O ₇ ) and vaporized at a temperature of 150 ° C. or higher. It is described that it accumulates in gin. It is also described that extraction of smoke gin with water absorbs rhenium oxide (Re ₂ O ₇ ) into an aqueous solution, and that the aqueous solution contains a large amount of sulfur dioxide and sulfur trioxide and thus exhibits strong acidity. .

JP-A-62-148327 Japanese Patent Laid-Open No. 2-20575 JP 47-21323 A

Although a method for producing perrhenic acid from crude rhenium sulfide by a wet process as in Patent Document 1 is known, it is also desirable to provide a method for producing perrhenic acid from crude rhenium sulfide by a dry process. In this regard, Patent Document 3 describes that rhenium sulfide is oxidized and changed to rhenium oxide by roasting, and that rhenium oxide is vaporized at a temperature of 150 ° C. or higher and accumulated in smoke gin. There is still room for improvement regarding the removal of impurities.

Therefore, an object of the present invention is to provide a method capable of producing high-purity perrhenic acid from rhenium sulfide using a dry process.

As a result of intensive studies to solve the above problems, the present inventors roast rhenium sulfide and extract rhenium as gasified rhenium oxide while separating non-volatile components such as zinc and bismuth as residues. Thereafter, the rhenium oxide is cooled and solidified. The sulfur content accompanies as a gaseous sulfur oxide, but can be removed by solid-gas separation by utilizing the difference in boiling point. This increases the purity of the recovered rhenium oxide. When the obtained rhenium oxide is dissolved in water, a high purity perrhenic acid aqueous solution is obtained.

The present invention has been completed based on the above findings, and in one aspect,
1) A process of roasting rhenium sulfide in the presence of an oxygen-containing gas and recovering gasified rhenium oxide;
2) a step of increasing the purity of rhenium oxide by cooling and solidifying the rhenium oxide while keeping the sulfur oxide accompanying the gasified rhenium oxide in a gas state, and then solid-gas separation;
3) A step of obtaining a perrhenic acid aqueous solution by dissolving the solidified rhenium oxide in water or by dissolving the solidified rhenium oxide in water after heating and gasifying;
Is a method for producing an aqueous solution of perrhenic acid.

In another aspect of the present invention,
1) Rhenium sulfide containing at least one of zinc and bismuth is roasted in the presence of an oxygen-containing gas, and at least one of zinc and bismuth is separated as a roasting residue to recover gasified rhenium oxide. Process,
2) a step of increasing the purity of rhenium oxide by cooling and solidifying the rhenium oxide while keeping the sulfur oxide accompanying the gasified rhenium oxide in a gas state, and then solid-gas separation;
3) A step of obtaining a perrhenic acid aqueous solution by dissolving the solidified rhenium oxide in water or by dissolving the solidified rhenium oxide in water after heating and gasifying;
Is a method for producing an aqueous solution of perrhenic acid.

In one embodiment of the method for producing a perrhenic acid aqueous solution according to the present invention, roasting is performed at a furnace atmosphere temperature of 200 to 600 ° C.

In another embodiment of the method for producing a perrhenic acid aqueous solution according to the present invention, the oxygen-containing gas is preheated to 100 ° C. or higher.

In yet another embodiment of the method for producing an aqueous perrhenic acid solution according to the present invention, in the step of cooling and solidifying the gasified rhenium oxide, the solidified rhenium oxide is recovered on a material insoluble in rhenic acid. The

Further another aspect of the present invention is a method for producing potassium perrhenate using a perrhenic acid aqueous solution obtained by the method for producing a perrhenic acid aqueous solution according to the present invention as a raw material.

In yet another aspect, the present invention is a method for producing ammonium perrhenate using a perrhenic acid aqueous solution obtained by the method for producing a perrhenic acid aqueous solution according to the present invention as a raw material.

Further another aspect of the present invention is a method for producing rhenium metal using a perrhenic acid aqueous solution obtained by the method for producing a perrhenic acid aqueous solution according to the present invention as a raw material.

According to the present invention, a dry process capable of producing high-purity perrhenic acid from rhenium sulfide is provided. The present invention can be incorporated into a process for producing ammonium perrhenate from rhenium sulfide.

It is a schematic diagram of the roasting equipment used for the roasting in an Example.

In one embodiment of the method for producing a perrhenic acid aqueous solution according to the present invention,
1) A process of roasting rhenium sulfide in the presence of an oxygen-containing gas and recovering gasified rhenium oxide;
2) a step of increasing the purity of rhenium oxide by cooling and solidifying the rhenium oxide while keeping the sulfur oxide accompanying the gasified rhenium oxide in a gas state, and then solid-gas separation;
3) A step of obtaining a perrhenic acid aqueous solution by dissolving the solidified rhenium oxide in water or by dissolving the solidified rhenium oxide in water after heating and gasifying;
including.

In another embodiment of the method for producing a perrhenic acid aqueous solution according to the present invention,
1) Rhenium sulfide containing at least one of zinc and bismuth is roasted in the presence of an oxygen-containing gas, and at least one of zinc and bismuth is separated as a roasting residue to recover gasified rhenium oxide. Process,
2) a step of increasing the purity of rhenium oxide by cooling and solidifying the rhenium oxide while keeping the sulfur oxide accompanying the gasified rhenium oxide in a gas state, and then solid-gas separation;
3) A step of obtaining a perrhenic acid aqueous solution by dissolving the solidified rhenium oxide in water or by dissolving the solidified rhenium oxide in water after heating and gasifying;
including.

(Rhenium sulfide)
The rhenium sulfide to be treated by the present invention may be rhenium sulfide containing no impurities or crude rhenium sulfide containing impurities. Typically, it is crude rhenium sulfide containing at least one of zinc and bismuth, and more typically crude rhenium sulfide containing both. In the present invention, “rhenium sulfide” refers to both crude rhenium sulfide containing impurities and rhenium sulfide substantially free of impurities. Although there is no restriction | limiting in the origin of crude rhenium sulfide, the crude rhenium sulfide derived from the following can be mentioned as a typical example.

In the waste acid obtained by washing the sulfurous acid gas generated from the smelting process of non-ferrous metals such as copper with water, rhenium contained in the raw ore is mixed with impurities. Such waste acid generally contains rhenium, bismuth, zinc, mercury, arsenic, iron, copper and the like. The rhenium in the spent acid exists in the form of rhenic acid (HReO ₄ ). By reacting rhenium in the waste acid with hydrogen sulfide, rhenium sulfide is produced, and can be recovered as a powder by solid-liquid separation. At this time, since zinc and bismuth do not react with hydrogen sulfide, they can be separated to the liquid side.

Impurities can also be removed by the following method to obtain rhenium sulfide with less impurities. For example, demercuration can be achieved by passing waste acid through a resin having a strong adsorptivity to mercury, such as a chelate resin or a strongly basic anion exchange resin. Moreover, the waste acid after demercuring is passed through an anion exchange resin, and rhenium and bismuth in the waste acid are selectively adsorbed on the resin, thereby removing arsenic, iron and copper that are not adsorbed on the resin. be able to. Rhenium and bismuth can be eluted from the anion exchange resin by passing an eluent such as hydrochloric acid through the anion exchange resin on which rhenium and bismuth are adsorbed. Separation of bismuth from rhenium can be performed by chromatography.

In a typical embodiment, in the crude rhenium sulfide, according to chemical analysis (other than mercury was analyzed by ICP-OES, mercury was analyzed by reductive vaporization spectrophotometry), rhenium: 30-66% by mass , Sulfur: 8 to 38 mass%, zinc: 0.01 to 1.0 mass%, bismuth: 0.01 to 1.0 mass%, mercury: 0.01 to 1.0 mass%, more typical In a specific embodiment, in the crude rhenium sulfide, rhenium: 35-50% by mass, sulfur: 25-32% by mass, zinc: 0.01-0.5% by mass, bismuth: 0.01-0. 7% by mass, mercury: 0.01 to 0.7% by mass. Part of rhenium may exist as rhenium oxide.

(Process 1)
In step 1, the rhenium sulfide is roasted in the presence of an oxygen-containing gas. By roasting, rhenium sulfide is considered to be converted to rhenium oxide according to the following reaction formula.
Re ₂ S ₇ (s) + 21 / 2O ₂ → Re ₂ O ₇ (s) + 7SO ₂ (g) (Formula 1)
SO ₂ (g) + 1 / 2O ₂ (g) → SO ₃ (g)
As can be seen from Equation 1, sulfur oxide is produced as a by-product. Rhenium oxide and sulfur oxide are gasified and discharged from the roasting furnace. When at least one of zinc and bismuth is contained in the roasting residue, it is preferable to recover these in the roasting residue.

The type of furnace for carrying out roasting is not particularly limited, and examples include a kiln furnace, a fluidized bed furnace, a tubular furnace, etc. preferable.

Also, it is desirable that an inert gas such as nitrogen or argon can be supplied into the furnace in order to suppress the reaction when the ambient temperature rises rapidly.

Examples of the oxygen-containing gas include oxygen, air, a mixture of oxygen and an inert gas, etc., but air is preferable because the cost increases. The oxygen-containing gas mentioned here is generated by using a solid or liquid (for example, potassium chlorate or ammonium perchlorate) that generates oxygen when heated, in addition to the oxygen-containing gas that exists in the gas from the beginning. Also included are oxygen-containing gases. From the viewpoint of reaction efficiency, the oxygen-containing gas is preferably supplied with oxygen equal to or higher than the theoretical equivalent required in the above (formula 1), for example, 1.2 or higher, and 1.8 or higher. It is more preferable.

In order to promote the gasification of rhenium oxide, it is desired to perform roasting at a relatively high furnace temperature in the roasting furnace. However, if an excessively high temperature is set, zinc content and bismuth content may be gasified. Therefore, roasting is preferably performed at an atmosphere temperature of the roasting furnace of 200 to 600 ° C, and roasted at 300 to 550 ° C. It is more preferable to perform roasting, and it is even more preferable to perform roasting at an atmosphere temperature of the roasting furnace of 350 to 500 ° C. The roasting time depends on the scale and structure of the roasting furnace, but if it is too long, the energy loss increases, but if it is too short, the non-volatility increases. Therefore, for example, 30 to 240 minutes is preferable. 120 to 180 minutes is more preferable.

It is desirable to preheat the oxygen-containing gas before supplying it to the roasting furnace. By preheating the oxygen-containing gas, the merit of uniform reaction in the furnace can be obtained. Specifically, the oxygen-containing gas is preferably preheated to the same temperature as the furnace atmosphere temperature. However, preheating more than necessary will result in energy loss.

Gas pipes may be used to transport gasified rhenium oxide. It is preferable to keep the gas piping warm and prevent rhenium oxide from adhering to the inner wall of the piping during transportation. If the temperature in the pipe during the heat retention is too low, rhenium oxide may solidify, so it is preferably set to 300 ° C. or higher, and it is not necessary to raise the temperature more than necessary from the viewpoint of energy consumption. C. or less, more typically 400.degree. C. or less.

(Process 2)
Then, the purity of rhenium oxide is increased by cooling and solidifying the rhenium oxide while keeping the sulfur oxide accompanying the gasified rhenium oxide in a gas state, and then solid-gas separating it. From the viewpoint of improving work efficiency, it is preferable to cool and solidify in a predetermined cooling place (in a pipe or in a container having an inlet / outlet). At this time, the accompanying sulfur oxide passes through the cooling place as a gas as it is due to the difference in boiling point, so that the purity of rhenium oxide is improved by solid-gas separation. From the viewpoint of preventing contamination, the solidified rhenium oxide is preferably recovered on a material insoluble in rhenic acid, such as quartz or glass, and recovered in a pipe or container using these materials as the inner wall material. Can do. During solid-gas separation, a filter may be installed to increase the recovery rate of rhenium. Cooling includes natural cooling, heat exchange, and the like, but it is preferable to carry out natural cooling for reasons of simplification of the apparatus.

The rhenium oxide can be completely solidified by cooling to 100 ° C. or lower, preferably 80 ° C. or lower. If the temperature is lower than necessary, the sulfur oxide that flows together with the rhenium oxide from the roasting furnace will be liquefied or solidified and recovered, so in order to completely exclude the sulfur oxide, the sulfur oxide must be above the boiling point of SO _3. Although it is preferable to cool to a temperature of 50 ° C. or higher, usually the form of the generated sulfur oxide is SO ₂ , so even if it is cooled to room temperature (eg 5 to 30 ° C.) above the boiling point of SO ₂ Good.

A method of directly obtaining a perrhenic acid aqueous solution by dissolving gasified rhenium oxide in water while cooling with a wet scrubber or the like is also conceivable. Therefore, it is inferior to the method of solidifying rhenium oxide in terms of purity. Illustratively, the method of dissolving rhenium oxide in water increases the S grade in the perrhenic acid aqueous solution by about 5 to 10 times compared to the method of solidifying rhenium oxide.

(Process 3)
In step 3, the solidified rhenium oxide is dissolved in water, or the solidified rhenium oxide is heated to gasify and then dissolved in water to obtain a perrhenic acid aqueous solution. It is thought that rhenium oxide is converted to perrhenic acid according to the following reaction formula.
Re ₂ O ₇ (s or g) + H ₂ O (l) → 2HReO ₄ (l) (Formula 2)
Although rhenium oxide can be easily dissolved in water, it is considered that the reaction efficiency decreases when the concentration in the aqueous solution is too high. On the other hand, if the concentration is too low, the amount of water used increases, handling properties during operation deteriorate, and a concentration step is required thereafter. Therefore, the input amount of rhenium oxide into water is preferably 50 to 500 g / L, and more preferably 150 to 250 g / L.

The method of dissolving solidified rhenium oxide in solid-liquid contact is a simple method, but after heating the solidified rhenium oxide to gasify again, it is gas-liquid contacted with a scrubber etc. and dissolved in water Is also possible. However, since this method causes an unrecovered loss, the former method is more preferable.

From the perrhenic acid aqueous solution, potassium perrhenate can be produced by any known method, and further ammonium perrhenate can be produced. For example, potassium perrhenate can be precipitated by adding potassium hydroxide to a perrhenic acid aqueous solution to adjust the pH to about 11 to 13, and this can be recovered by solid-liquid separation. Further, since potassium perrhenate is heavy and easily settles, it is preferable to separate solid-liquid separation after separating impurities that are likely to float. In addition, the purity can be increased by a water tank or the like. A rhenium metal can be produced by reducing potassium perrhenate with hydrogen or the like (see, for example, JP-A-62-124240).

Further, ammonium perrhenate can be produced by adding ammonia water to a perrhenic acid aqueous solution and adjusting the pH to about 7 to 12 to precipitate ammonium perrhenate and performing solid-liquid separation. By repeating the purification, the purity can be further increased. Examples of the purification method include a method of re-dissolution in pure water and crystallization. After neutralization, it is preferably concentrated by heating to 90 to 105 ° C. before solid-liquid separation. A rhenium metal can be produced by reducing ammonium perrhenate with hydrogen or the like (see, for example, JP-A-62-146227).

Examples of the present invention will be described below, but the examples are for illustrative purposes and are not intended to limit the invention.

(Examination of the influence of roasting conditions on the gasification rate of each component)
Crude rhenium sulfide having the analytical values shown in Table 1 was prepared. The content of each component was measured by chemical analysis (analyzed by ICP-OES).

The crude rhenium sulfide 500 g was roasted for 120 to 140 minutes under various kiln furnace atmosphere temperature conditions, and then cooled to room temperature. A kiln furnace was used as the roasting furnace, and air was used as the oxygen-containing gas. In all examples, the oxygen equivalent was in the range of 1.9 to 2.2. Further, it was found that when the air was preheated to a predetermined temperature (140 ° C. in this case) and then supplied to the kiln furnace, the atmosphere temperature in the furnace stabilized and the volatility of sulfur tended to increase. The weight of the residue after the test was measured, and chemical analysis of the residue was performed. The content (g) of each element was determined from the weight of the residue and each elemental analysis result, and the gasification rate was determined from the difference in content (g) before and after the test.
The roasting time is the time from when the atmospheric temperature in the kiln furnace reaches a predetermined temperature until the cooling is started. The oxygen equivalent is based on the assumption that the rhenium and sulfur contained in the crude rhenium sulfide is Re ₂ S ₇ or present in a form other than oxide, all rhenium up to Re ₂ O ₇ and all sulfur is SO. The theoretical oxygen equivalent until the reaction up to ₃ was calculated as 1.
As a result, when the kiln furnace atmosphere temperature is 100 ° C. or more and less than 200 ° C., the Re gasification rate is about 10% or more and less than 20%, and when the kiln furnace atmosphere temperature is 200 ° C. or more, it becomes 20% or more. When the furnace atmosphere temperature was 350 ° C. or higher, it was 40% or higher. The gasification rate of S was 10% or more when the kiln furnace atmosphere temperature was 100 ° C. or higher, and 80% or more when 300 ° C. or higher. Therefore, it was confirmed that separation in the subsequent process of S is important.
The gasification rates of Zn and Bi were substantially 0% when the kiln furnace atmosphere temperature was less than 600 ° C.

(Verification of effects of solid-gas separation)
Crude rhenium sulfide having the analytical values listed in Table 2 was prepared. The content of each component was measured by chemical analysis (analyzed by ICP-OES).

The 531 g of the crude rhenium sulfide was roasted using the roasting equipment shown in FIG. 1 under the conditions shown in Table 3-1. Thereafter, the furnace was cooled to room temperature. A tubular furnace 10 was used as a roasting furnace, and air 16 was supplied as an oxygen-containing gas at a flow rate of 1.5 L / min. Similarly to the above example, the S gasification rate, the S quality in the roasting residue, the Re gasification rate, the Zn gasification rate, and the Bi gasification rate were determined. The results are shown in Table 3-2.

Next, after the gasified component containing rhenium oxide is transported for a certain distance in a gasified state in the tubular furnace external reaction tube heat retaining portion 14 kept at 300 ° C., the inner wall of the quartz reaction tube 13 is not kept warm. The solid was cooled and precipitated as solid rhenium oxide 18. In addition, the gas temperature was in the state cooled to room temperature (about 30 degreeC) on the way from the heat insulation part to the scrubber. The gas exiting the reaction tube absorbed sulfur oxides with a scrubber 15 to render the gas harmless and discharged. The reaction tube 13 on which rhenium oxide 18 was deposited was removed, and normal temperature water was passed through the reaction tube 13 to dissolve the rhenium oxide to obtain a perrhenic acid aqueous solution. The concentration of each component in the aqueous perrhenic acid solution obtained was measured by chemical analysis (analyzed by ICP-OES), and the recovery rate of each component when the concentration in crude rhenium sulfide was taken as the standard (100%) was calculated. Asked. The results are shown in Tables 4-1 and 4-2.

The obtained aqueous perrhenic acid solution was neutralized by adding ammonium water until the pH reached 9, and then solid-liquid separation was performed to obtain ammonium perrhenate (APR) powder. The analysis results of ammonium perrhenate are shown in Table 5. Analysis was performed by GDMS.

DESCRIPTION OF SYMBOLS 10 Tubular furnace 11 Sample 12 Sample place 13 Reaction tube 14 Reaction tube heat insulation part 15 Scrubber 16 Air 17 Exhaust 18 Rhenium oxide

Claims (8)

1. 1) A process of roasting rhenium sulfide in the presence of an oxygen-containing gas and recovering gasified rhenium oxide;
   2) a step of increasing the purity of rhenium oxide by cooling and solidifying the rhenium oxide while keeping the sulfur oxide accompanying the gasified rhenium oxide in a gas state, and then solid-gas separation;
   3) A step of obtaining a perrhenic acid aqueous solution by dissolving the solidified rhenium oxide in water or by dissolving the solidified rhenium oxide in water after heating and gasifying;
   The manufacturing method of the perrhenic acid aqueous solution containing this.
2. 1) Rhenium sulfide containing at least one of zinc and bismuth is roasted in the presence of an oxygen-containing gas, and at least one of zinc and bismuth is separated as a roasting residue to recover gasified rhenium oxide. Process,
   2) a step of increasing the purity of rhenium oxide by cooling and solidifying the rhenium oxide while keeping the sulfur oxide accompanying the gasified rhenium oxide in a gas state, and then solid-gas separation;
   3) A step of obtaining a perrhenic acid aqueous solution by dissolving the solidified rhenium oxide in water or by dissolving the solidified rhenium oxide in water after heating and gasifying;
   The manufacturing method of the perrhenic acid aqueous solution containing this.
3. The method for producing a perrhenic acid aqueous solution according to claim 1 or 2, wherein the roasting is performed at an atmospheric temperature in the furnace of 200 to 600 ° C.
4. The method for producing a perrhenic acid aqueous solution according to any one of claims 1 to 3, wherein the oxygen-containing gas is preheated to 100 ° C or higher.
5. 5. The method for producing an aqueous perrhenic acid solution according to claim 1, wherein in the step of cooling and solidifying the gasified rhenium oxide, the solidified rhenium oxide is recovered on a material insoluble in rhenic acid. .
6. A method for producing potassium perrhenate using a perrhenic acid aqueous solution obtained by the method for producing a perrhenic acid aqueous solution according to any one of claims 1 to 5 as a raw material.
7. A method for producing ammonium perrhenate using a perrhenic acid aqueous solution obtained by the method for producing a perrhenic acid aqueous solution according to any one of claims 1 to 5 as a raw material.
8. A method for producing rhenium metal using a perrhenic acid aqueous solution obtained by the method for producing a perrhenic acid aqueous solution according to any one of claims 1 to 5 as a raw material.

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